In recent years, use of the ultra-fine processing technology for forming a few micrometers depression and projection in the tire surface of a pneumatic tire (hereinafter, referred to as “tire”) is popularizing (for example, refer to Patent Literature 1).
Such an ultra-fine processing technology is expected as one of the art effective in inhibition of rotation resistance of a tire. Specifically, there is frictional resistance of air (open air) as one of the causes which rotation resistance generates. With the ultra-fine processing technology mentioned above, when a tire rotates, the tire by which depression and projection were formed in the tire surface makes the tire surface generate the turbulent flow of air intentionally, and can form the relief layer of air in it. It is considered that the tire by which the relief layer of air was formed in the tire surface can control the rotation resistance of a tire because frictional resistance with the air positioned in the tire outer side direction of a relief layer can be reduced when a tire rotates.
However, in the tire related to conventional technology, although depression and projection can be formed in the tire surface with ultra-fine processing technology, the optimal shape and arrangement interval of the depression and projection are not taken into consideration. As a result, in the tire related to conventional technology, when a tire rotated, the relief layer of air was disturbed and there was a problem that rotation resistance could not fully be controlled.